Bandwidth enhancement of calcium ferrite-graphite nanocomposite microwave absorber using single square loop frequency selective surface

Abstract

Radar wave absorbers are important for the reduction of radar cross section of the target for stealth applications. A wide variety of materials are currently being used for microwave absorption in different frequency bands. Due to recent advancement in radar technology, radars are now available from 2–18 GHz frequency range. So it becomes quite challenging to develop simple new materials that can work as wide band radar wave absorber. For this purpose the selection of material is very important as the radar wave absorption depends primarily upon the material characteristics i.e., complex permittivity and complex permeability and conductivity of the material. Therefore, an attempt has been made to develop a radar wave absorbing nano-composite by selecting constituent materials with such inherent properties that can work for the absorption of radar wave for wide frequency range. It is observed that the developed composite gives good absorption but with narrow radar wave absorption bandwidth (8.7 GHz to 10.5 GHz). Effect of carbonous material has been investigated on the absorption properties of the developed nanocomposite so as to extend the radar wave absorption towards the lower frequency range of 6.7 GHz to 10.2 GHz. Further the possibility of the efficient use of an advanced electromagnetic technique like frequency selective surfaces has been explored to enhance the radar wave absorption bandwidth. Simple FSS geometry i.e. single square loop has been investigated such that complexity due to FSS can be avoided. It has been observed that the synthesised single layer absorber with single square loop FSS is able to provide radar wave absorption bandwidth in the frequency range of 5.75 GHz to 12.75 GHz.